Rowella haeckeliana, (POLEJAEFF, 1883), Lopes & Klautau, 2023

Lopes, Matheus Vieira & Klautau, Michelle, 2023, Phylogeny and revision of Leucaltis and Leucettusa (Porifera: Calcarea), with new classification proposals and description of a new type of aquiferous system, Zoological Journal of the Linnean Society 198, pp. 691-746 : 724-727

ROWELLA HAECKELIANA ( POLÉJAEFF, 1883) COMB. NOV.

( FIGS 18, 19; TABLE 10 )

Synonyms: Leucetta haeckeliana – Poléjaeff, 1883: 69; Fell, 1950: 10; Leucettusa haeckeliana – Dendy & Row, 1913: 739; Burton, 1932: 261; 1963: 553; Lopes et al., 2018a: 59; Riesgo et al., 2018: 837; Leucilla haeckeliana – Fell, 1950: 10; Leucettusa sp. 1 – Voigt et al., 2012: 3.

Type specimen: Three syntypes ( BMNH 1884.22.62-64).

Type locality: Off Sydney, New South Wales, Australia (33°51ʹ S, 151°15ʹ E). Manning-Hawkesbury MEOW ecoregion.

Description: Sponges formed by individual tubes with vase-shaped body, widening at the distal part and again narrowing towards the osculum ( Fig. 18A). Colour light brown to cream white in ethanol. Compressible and soft, but firm. The outer surface is smooth, while the atrial surface is slightly hispid due to the apical actines of tetractines. Each tube has a single apical osculum. Oscula are circular and surrounded by membrane ( Fig. 18B). Aquiferous system leuconoid with spherical choanocyte chambers and many large canals ( Fig. 18C).

Skeleton: The oscular margin has a skeleton comprised of large sagittal triactines ( Fig. 19A) and tetractines and pygmy triactines and tetractines that gradually become regular as the body wall thickens. The cortical skeleton is well developed, being almost as thick as the choanosome ( Fig. 18C). It is comprised of many layers of tangential triactines ( Fig. 18D) and of rare tetractines. The tetractines project their apical actine into the choanosome, but it never penetrates the atrial cavity. The choanosomal skeleton is reduced and comprised of pygmy tetractines ( Fig. 18E), mostly present around the canals. Pygmy tetractines are also present in the atrial skeleton, laying tangentially, projecting their apical actine into the atrial cavity ( Fig. 18F). Few pygmy triactines were observed in the choanosome and the atrium.

Spicules ( Table 10 ):

Cortical triactines ( Figs 19A–C). Regular to sagittal. Variable sizes. Actines are cylindrical and straight, with blunt to sharp tips. Nearby the oscular margin, they acquire a sagittal shape. Size – 423.0 (± 89.7) μm length/22.0 (± 4.4) μm width.

Cortical tetractines ( Fig. 19D). Regular to sagittal. Rare. Basal actines slightly conical, straight, with blunt tips. The apical actine is conical, straight and smooth, with blunt to sharp tips. They are frequently longer than the basal ones. Nearby the oscular margin, they acquire a sagittal shape. Size – basal actines: 505.0 (± 162.6) μm length/55.5 (± 7.0) μm width; apical actine:> 600.0 μm length/70.0 (± 7.2) μm width.

Choanosomal and atrial triactines ( Fig. 19E). Regular to sagittal. Pygmy. Rare. Actines are thicker at the base, slightly conical to conical, straight with sharp tips. Nearby the oscular margin, they acquire a sagittal shape. Size – 53.3 (± 15.1) μm length/8.3 (± 1.4) μm width.

Choanosomal and atrial tetractines ( Fig. 19F). Regular to sagittal. Pygmy. Basal actines are thicker at the base, conical, straight with sharp tips. The apical actine is longer than the basal ones, conical, smooth, sharp and straight or slightly curved at the distal part ( Fig. 18F). Nearby the oscular margin, they acquire a sagittal shape. Size – basal actines: 41.6 (± 18.0) μm length/8.0 (± 1.0) μm width; apical actine: 68.8 (± 11.2) μm length/7.8 (± 0.6) μm width.

Ecology: This species was found in stones and soft bottoms, such as sand and shells. Depth range 55–2000 m.

Geographical distribution (MEOW ecoregions): Manning-Hawkesbury (off Sydney – Poléjaeff, 1883), Bassian (Ling Hole, Tasmania – Voigt et al., 2012), Agulhas Bank ( South Africa – Burton, 1963, probably inaccurate), Malvinas /Falklands ( Falkland Islands – Burton, 1932, probably inaccurate).

Remarks: Leucetta haeckeliana was described by Poléjaeff (1883) based on three specimens collected during the Challenger Expedition from Australian waters. Currently, there is only one small fragment of a syntype under the voucher number BMNH 1884.22.62-64. Other fragments of the syntype are possibly deposited in Kirk’s Collection at the Zoology Museum of Victoria University, Wellington, under the name Leucilla haeckeliana ( Fell, 1950) .

Poléjaeff (1883) mentioned the presence of large triactines and (rare) tetractines in the cortex, and pygmy tetractines in the choanosome/atrium. After re-analysing the holotype skeleton, we also found pygmy triactines in the choanosome and atrium. Pygmy spicules of R. haeckeliana sometimes have two curved actines, showing differentiation between paired (curved) and unpaired (straight) actines. We observed that they occur mostly around the oscular margin, becoming regular as the body wall thickens. RoƜella lancifera also has pygmy spicules with curved actines all over the body. However, in this species the three actines can be bent in different directions, like a pinwheel.

Burton (1963) widened the distribution of RoƜella haeckeliana from the Pacific Ocean to South Africa (Indian Ocean; Burton, 1963) and Falkland Islands (South Atlantic; Burton, 1932), but he gave no descriptions or any taxonomic remarks. We did not analyse these specimens (BMNH 1934.11.20.33 and 1928.2.15.711-714, 847, respectively), but we suspect that the Falkland material is R. simplicissima , because this is the type locality of that species. Burton (1932) also stated that R. haeckeliana was known from Kerguelen. This is probably incorrect because the type locality of R. haeckeliana is Sydney, eastern Australia. The only RoƜella known to date from Kerguelen is R. Ʋera .